Update sourcemap test to match updates in Libsass

test/fixtures/source-map/expected.map

@@ -5,6 +5,6 @@
 		"index.scss"
 	],
 	"sourcesContent": [],
-	"mappings": "AAAA,OAAO,CAAC;EACN,KAAK,EAAE,GAAI;EACX,MAAM,EAAE,IAAI,GAFL;;AAKD,OAAO,CAAC,EAAE,CAAP;EACT,eAAe,EAAE,IAAK,GADZ;;AAIJ,OAAO,CAAC,EAAE,CAAP;EACT,KAAK,EAAE,IAAK,GADF;EAGV,OAAO,CAAC,EAAE,CAAC,CAAC,CAAV;IACA,WAAW,EAAE,IAAK,GADjB",
+	"mappings": "AAAA,OAAO,CAAC;EACN,KAAK,EAAE,GAAI;EACX,MAAM,EAAE,IAAK,GAFN;;AAKD,OAAO,CAAC,EAAE,CAAP;EACT,eAAe,EAAE,IAAK,GADZ;;AAIJ,OAAO,CAAC,EAAE,CAAP;EACT,KAAK,EAAE,IAAK,GADF;EAGV,OAAO,CAAC,EAAE,CAAC,CAAC,CAAV;IACA,WAAW,EAAE,IAAK,GADjB",
 	"names": []
 }